基于红外和可见光图像逐级自适应融合的场景深度估计

从图像中恢复场景的深度是计算机视觉领域中的一个关键问题。考虑到单一类型图像在深度估计中受场景不同光照的限制,提出了基于红外和可见光图像逐级自适应融合的场景深度估计方法（PF-CNN）。该方法包括双流滤波器部分耦合网络、自适应多模态特征融合网络以及自适应逐级特征融合网络。在双流卷积中红外和可见光图像的滤波器部分耦合使两者特征得到增强;自适应多模态特征融合网络学习红外和可见光图像的残差特征并将两者自适应加权融合,充分利用两者的互补信息;逐级特征融合网络学习多层融合特征的结合,充分利用不同卷积层的不同特征。实验结果表明:PF-CNN在测试集上获得了较好的效果,将阈值指标提高了5%,明显优于其他方法。     

Acousto-optic collinear diffraction of arbitrarily polarized light

Collinear acousto-optic diffraction of arbitrarily polarized light is studied. It is shown that in the general case, the diffraction spectrum at the output of an acousto-optic cell contains four components, which have different frequencies and polarizations. Beats of these components lead to modulation of the intensity of light transmitted through the output analyzer. The amplitudes of the transmitted light components are analyzed as functions of the frequency and power of the acoustic wave for different polarizer and analyzer orientations. Experimental investigations are carried out in a calcium molybdate collinear cell.     

Acousto-optic control of light beams in the infrared range

The control over the parameters of the far-infrared and terahertz radiation by the acoustooptic method is discussed. The operation of a tunable acousto-optic filter based on the tellurium crystal is investigated. The crystal used in the filter was transparent for the optic radiation in the wavelength range of 4.0 to 23 µm. The device allows electronic tuning and processing of optic images in the spectral interval of 8.0 to 14 µm.     

单光子探测三维点云与可见光图像融合处理算法研究

为了提升光电系统对于目标的探测识别能力,实现单光子探测三维点云数据和二维可见光图像的融合处理,提出了单光子探测成像系统的融合处理算法,采用直接线性变换方法并利用同名特征点的选取和间接平差算法解决了融合处理过程中的参数标定问题。通过实验数据进行融合处理算法验证,实现了分辨率1024×768像素单光子探测三维点云和二维可见光图像的像素级融合处理。实验结果表明,提出的融合处理算法能够有效实现三维、二维图像的融合。     

Acousto-optic mode coupling of partially coherent light in two-mode optical fibers

An acoustic pulse propagating on a two-mode fiber can act as a beam splitter in a scanning interferometer. When this device is employed in white-light interferometry, the effects of distributed coupling and dispersive interferometer arms need to be considered. A theory suitable for treating acousto-optic interaction of partially coherent light in a moving interaction region was developed. It was found that differential optical dispersion should be negligible and the acoustic pulse length short. Also the coherence time should be short but long compared to the intermodal group delay difference over a pulse length. Experiments with long acoustic pulses were performed, and fairly good agreement with theory was obtained.     

Conversion of ultraviolet and infrared to visible light in Er3+ and Dy3+ co-doped CsGd2F7

The CsGd₂F₇ crystal co-doped with 1 at% Er³⁺ and 0.2 at% Dy³⁺ ions was studied using the excitation of both synchrotron radiation and 355 nm laser. All the emission bands were assigned by using the Dieke diagram together with the conclusions from relaxation kinetics studies. The onset of the 4f–5d transition bands and the centers of charge transfer bands were also calculated for the lanthanide series CsLn₂F₇ and the results were used to assign the bands and peaks in the excitation spectra. The energy transfer and relaxation processes in CsGd₂F₇ were thoroughly analyzed. Quantum cutting downconversion of one vacuum ultraviolet to two visible photons was realized under 154 nm excitation. Upconverted green emission was observed under 980 nm excitation.     

Effect of different doped elements on visible light absorption and ultraviolet light emission on Er3+:Y3Al5O12

In this progress report, seven kinds of novel carefully designed and fabricated up-conversion luminescence agents, Er³⁺:Y₃Al₅O₁₂, Er³⁺:Yb_nY_3?nAl₅O₁₂, Er³⁺:Y₃B_aAl_5?aO₁₂, Er³⁺:Y₃Ga_bAl_5?bO₁₂, Er³⁺:Y₃Al₅N_xO_12?x, Er³⁺:Y₃Al₅F_yO_12?y and Er³⁺:Yb_nY_3?nB_aGa_bAl_5?a?bN_xF_yO_12?x?y, are successfully synthesized using sol–gel methods. After that, their corresponding photocatalysts, Er³⁺:Y₃Al₅O₁₂/TiO₂, Er³⁺:Yb_nY_3?nAl₅O₁₂/TiO₂, Er³⁺:Y₃B_aAl_5?aO₁₂/TiO₂, Er³⁺:Y₃Ga_bAl_5?bO₁₂/TiO₂, Er³⁺:Y₃Al₅N_xO_12?x/TiO₂, Er³⁺:Y₃Al₅F_yO_12?y/TiO₂ and Er³⁺:Yb_nY_3?nB_aGa_bAl_5?a?bN_xF_yO_12?x?y/TiO₂, are also prepared by sol–gel coating process. The obtained up-conversion luminescence agents and photocatalysts were characterized by using XRD, XPS, SEM, UV–vis and fluorescence spectrophotometer. Synchronously, several kinds of organic dyes are used to test their photocatalytic degradation using prepared photocatalysts. It indicates that the up-conversion luminescence ability of Er³⁺:Y₃Al₅O₁₂ can be improved obviously through doping of some elements. And then, the photocatalytic activity of TiO₂ is markedly enhanced by modified up-conversion luminescence agents which can transform much visible light into ultraviolet light.     

用于扩频通信的声光循环平稳信号处理技术

传统的基于声光技术的信号处理模型被建模为平稳随机过程,而在扩频通信中,信号是被伪码调制的循环(周期)平稳信号。因此,扩频信号应被建模为循环平稳随机过程。基于声光信号处理技术和循环平稳随机过程理论,建立了声光循环平稳信号处理模型,并应用于扩频通信中,理论分析和仿真表明,声光循环平稳信号处理技术在扩频通信领域的信号分析中是十分有用的。     

声光自适应信号处理技术在扩频通信中的应用

研究了声光滤波的工作原理,用布拉格器件作模拟抽头延迟线完成横向滤波。讨论了LMS自适应滤波的基本方法,给出了声光自适应LMS滤波的实现方法并用于扩频通信的窄带干扰抑制中。对扩频通信进行干扰抑制的滤波过程通常是一个自适应过程,采用声光自适应滤波技术,不仅能抑制窄带干扰,而且能提高系统的处理增益和分辨率。     

Acousto-optic device-based high-speed high-isolation photonic switching fabric for signal processing

A high-speed, switched, binary photonic switching fabric based on two acousto-optic devices arranged in a compact self-aligning (by acousto-optic device-based Bragg matching) optical geometry is introduced for photonic signal processing and control. This fabric has the unique capability to provide simultaneously both high switching speeds and high optical isolation, a critical need for advanced low-noise high-speed signal-processing applications. The proof-of-concept experimental fabric demonstrated nearly 60% light throughput, a 39-dB optical isolation level for both states of the switching fabric, and a 138-ns switching time.     

外场紫外与可见光双波段可调焦装置校准设计

设计了一种用来校准紫外与可见光光轴平行性的可调焦光学系统,调焦范围为70 m~。针对目前大多数校准系统无法进行调焦的问题,提出一种既能校准紫外与可见光光轴平行性又能对紫外部分进行调焦的方法。采用离轴卡塞格林系统作为初始结构进行设计,通过在传统的卡塞格林系统中加入调焦组和补偿组来实现调焦以及像差补偿,所设计的系统可以有效地解决紫外与可见光双光轴平行性失调的校准问题,提高紫外与可见光双光轴平行性校准效率,并且在不同视距下光学传递函数值及点列斑均接近衍射极限,能量集中度达到90%,整个视场的像质均匀,像面清晰,有利于后续的图像处理工作。     

Acousto-optic light deflection in an Al2O3 optical waveguide structure

The total deflection of an optical guided wave by a surface acoustic wave (SAW) in a silicon-based SiO₂/AL₂O₃/SiO₂ optical waveguide structure is reported. The SAW is generated by an interdigital transducer with piezoelectric ZnO deposited on top of the optical waveguide structure.     

一种基于区域生长的红外与可见光的图像融合方法

针对目前红外与可见光目标跟踪的视频序列融合难以满足实时性问题，利用红外图像目标与背景显著的灰度差异特征，结合目标跟踪中目标分割时常用到的区域生长法，通过区域生长方法从红外图像中提取目标区域，再将得到的红外目标区域与已经过图像配准的可见光图像的背景区域进行融合处理，最终得到既具有红外图像较好的目标指示特性又具有可见光图像清晰场景信息的融合图像。实验表明：该算法不仅简单易行，而且所得到的融合图像视觉效果优于其他融合算法得到的图像。     

Acousto-optic light deflection in an Al2O3 optical waveguide structure

The total deflection of an optical guided wave by a surface acoustic wave (SAW) in a silicon-based SiO₂/AL₂O₃/SiO₂ optical waveguide structure is reported. The SAW is generated by an interdigital transducer with piezoelectric ZnO deposited on top of the optical waveguide structure.     

Acousto-optic diffraction at liquid-solid interface with light incident at critical angle

A new acousto-optic diffraction configuration is described. At a liquid-solid interface, a light beam is incident from the solid side of higher refractive index. The maximum acousto-optic diffraction of the Raman-Nath type occurs in the liquid with light incident at the critical angle. The angular dependence of the diffraction efficiency indicates accurate optical alignment requirement. Application to acoustic imaging is briefly discussed.     

Super-transmission of light through subwavelength annular aperture arrays in metallic films: Spectral analysis and near-field optical images in the visible range

This paper presents experimental studies of the enhanced light transmission through metallic films pierced by subwavelength annular apertures. Two different methods (e-beam lithography and focused ion beam) have been used to build the nano-structures. We have experimentally recorded their far-field spectral response in the visible range and the optical near-field above the nano-structures when they are excited at 633 nm. The spectral response exhibits a transmission peak at 700 nm with maximum efficiency around 16%. The near-field exhibits a characteristic two-lobe structure just above the aperture. Finite difference time domain (FDTD) simulations reproduce quite well the experimental results.     

Acousto-optic generation of orbital angular momentum states of light in a tapered optical fiber

We demonstrate an acousto-optic mode converter based on a tapered optical fiber to efficiently generate orbital angular momentum states of light. In our scheme an acoustic wave is deployed to the waist of tapered optical fiber where two degenerate HE₂₁ modes leading to +1 and −1 orbital angular momentum eigen-modes are resonantly excited. The excitation of TM₀₁ and TE₀₁ modes is suppressed by enlarging the intermodal index difference between near-degenerate spatial modes. Numerical calculation for optimization of the taper diameter is provided. The experimental characterization of generated states is performed by analyzing the output far-field pattern and the spatial interference fringes with a uniform reference beam.     

Bright tunable ultraviolet squeezed light

We have produced bright tunable squeezed light by second-harmonic generation in a singly resonant cavity. We have investigated the effect of input coupling and fundamental power on the squeezing. Up to 400 mW of continuous-wave mode-locked tunable squeezed light was produced at wavelengths as short as 389 nm, and more than 1.5 dB of squeezing was inferred.     

Multiphoton ultraviolet and visible upconversion luminescence of TmYb co-doped oxyfluoride glass

The ultraviolet upconversion luminescence of Tm³⁺ ions sensitized by Yb³⁺ ions in oxyfluoride glass when excited by a 975 nm diode laser was studied in this paper. One typical ultraviolet upconversion luminescence lines positioned at 362.3 nm was found. It can be attributed to the five-photon upconversion luminescence transition of ¹D₂ → ³H₆. Several visible upconversion luminescence lines at 451.1 nm, (477.9 nm, 462.5 nm), 648.7 nm, (680.5 nm, 699.5 nm) and (777.5 nm, 800.7 nm) were found also, which results from the fluorescence transitions of five-photon ¹D₂ → ³F₄, three-photon ¹G₄ → ³H₆, three-photon ¹G₄ → ³F₄, two-photon ³F₃ → ³H₆ and two-photon ³H₄ → ³H₆ of Tm³⁺ ion, respectively. The theoretical analysis suggests that the upconversion mechanism of the 362.3 nm ¹D₂ → ³H₆ upconversion luminescence is the cross energy transfer of {³H₄(Tm³⁺) → ³F₄(Tm³⁺), ¹G₄(Tm³⁺) → ¹D₂(Tm³⁺)} and {¹G₄(Tm³⁺) → ³F₄(Tm³⁺), ³H₄(Tm³⁺) → ¹D₂(Tm³⁺)} between Tm³⁺ ions. In addition, the upconversion luminescence of ¹G₄ and ³H₄ state results from the sequential energy transfer {²F_5/2(Yb³⁺) → ²F_7/2(Yb³⁺), ³H₄(Tm³⁺) → ¹G₄(Tm³⁺)} and {²F_5/2(Yb³⁺) → ²F_7/2(Yb³⁺), ³F₄(Tm³⁺) → ³F₂(Tm³⁺)} from Yb³⁺ ions to Tm³⁺ions, respectively.